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Soybeans
Volume 53 Number 18 Date 08/22/2008 NORTHERN CORN ROOTWORM - Several fields examined in Columbia County showed light defoliation attributed to this insect. Although the level of feeding injury was inconsequential, approximately 40-65% of the plants distributed throughout the fields were affected, and very large numbers of beetles were observed (2-9 per plant). SOYBEAN APHID - Surveys of R2-R4 stage soybeans conducted earlier this month found 92% of the 277 fields examined contained non-economic populations of aphids. Despite these results, population densities have continued to build in recent weeks and numerous acres were sprayed between August 1 and 15. Chemical treatments are not recommended for fields at R6 (full seed) or later, since no yield benefit is gained. A small proportion of soybean fields still qualify for treatment, and these must be appraised now to determine if colonies have reached or surpassed the economic threshold of 250 aphids per plant on 80% of the plants. SOYBEAN APHID MUMMIES - One field in Columbia County contained counts as high as 140 mummies per plant, suggesting that parasitism by the minute wasp Lysephlebus testaceipes had caused considerable mortality. Parasitism by this species and Aphelinus albipodus, as evidenced by tan, brown or black aphid mummies, has been far more noticeable and widespread this season in comparison to previous years. --Krista Hamilton, DATCP Entomologist 
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